Sometimes user wants a class that isn't listed, well, you can role play as any medieval human class! Ninjas, Samurai, Pirate, Navy.
Just make sure your custom class kinda is related to our listed one.
Here are some examples:
Knight - Samurai, Barbarian, Gladiator
Assassin - Ninja, Ronin
Theft - Pirate, Ninja
Voyager - Pirate, Navy
Citizen - ...
But of course, you can choose your own too custom classes in certain class too.